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Stage 1 Pharmacy > Pharmaceutics > Flashcards

Pharmaceutics Flashcards

1
Q

Ideal properties of dosage forms

A 
Performance 
Acceptability to patients 
Acceptable large scale production 
Reproducible quality 
Physical and chemical stability for shelf life
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2
Q

Oral route administration benefits and problems

A

Most common and simple
Convenient and safe
High surface area therefore excellent absorption
modified release formulation available

Lag time to effective conc at site (slow onset)
Hostile environment (pH, enzymes)
Variability (patient info/diseased state)
First pass metabolism
Irritation to GI system
difficult to reverse therapy

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3
Q

What is first pass metabolism

A

Hepatic portal vein serves the gut and delivers absorbed material to the liver for metabolism
Therefore drug is greatly reduced before it reaches the systemic circulation

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4
Q

Solution

A

Homogeneous liquid system containing 2 or more components but administered as 1 phase

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5
Q

Parenteral route benefits and problems (commonly injection)

A 
Rapid onset 
No first pass metabolism 
Can be applied to patients unconscious 
can delay onset of action
Higher conc of drug in systemic circulation

Infection risk
Pain
Only liquid/suspension form administered (chemical and physical stability problems)
Irreversible
Requires health professional to administer
Shorter shelf life than of oral forms

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6
Q

Topical route benefits and problems

A

Non-invasive
Local treatment without systemic effect
Avoids GI degradation and first pass metabolism
Easy drug withdrawal in case of adverse effects
convenient

Not accurate dosage
Oily feeling on the skin therefore low patient compliance
Grade of systemic absorption
Absorption dependant on site (soft vs callused)
Skin irritation

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7
Q

Rectal route benefits and problems

A

Well vascularised region
Local use and systemic delivery
Avoid first pass metabolism
Possible to remove dosage and discontinue treatment
Suitable for the elderly
suitable for drugs liable to degrade in GIT or high first pass metabolism

Erratic absorption of drugs (absorption generally lower slower than oral route)
Rectal suppository/foams/enemas not often used in UK causes discomfort
Specialist advice on administration required
Can cause local side effects
Upward movement inc first pass metabolism

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8
Q

The Biopharmaceutics Classificatiom System

A

Groups drugs based on permeability and solubility. Predicts bioavailability

High S + High P = class 1 
Low S + High P = class 2
High S + Low P = class 3
Low S Low P = class 4
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9
Q

Factors that affect solubility

A

Temperature
Pressure
Molecular structure
pH

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10
Q

Gibbs equation

A

change in gibbs = enthalpy change - T x entropy change
Dissolution favoured if G < 0
G must be negative for reaction to be spontaneous

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11
Q

Tablets advantages and disadvantages

A

Convenient to take and handle
better chemical, physical and microbiological stability
precise dosing of drug
relatively cheap to mass produce
Poor drug bioavailability due to unfavourable drug properties
may cause local irritation
may cause GI mucosa damage

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12
Q

Tablet manufacturing

A

powder compression - 2 punches and a die

die filling, tablet formulation, tablet ejection

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13
Q

Tablet excipients

A 
Filler
Disintegrant
Binder
Glidant
Lubricant 
Anti-adherant
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14
Q

Advantages and disadvantages of capsules

A 
Easy to swallow
Easy to handle
Easy to identify
Mask taste and smell
Minimal excipients needed

Product cost more than tablets
not suitable for highly soluble substances
not suitable for highly deliquescent materials

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15
Q

Excipients for oral route

A 
1) Viscosity enhancers
preservatives
sweeteners
2) Antioxidants
flavouring agents
colouring agents
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16
Q

Suspensions advantages and disadvantages

A

Same ad solution
Rate of absorption lower than solution
Dose uniformity only assured if the suspension is homogenous

17
Q

suspension excipients

A 
1) Flavours
sweeteners
colours
2) Preservatives 
Buffers
3) Suspending agents (viscosity modifiers)
4) Chemical stabilisers
wetting agents 
5) Flocculation modifiers
18
Q

Parenteral excipients

A 
Vehicle for injection - Water, Saline, Solubilising agent
Preservative 
Antioxidants
pH adjusters and buffers
Tonicity adjusting agents
Suspending agents
19
Q

compaction cycle

A

filling, compression, ejection

20
Q

mechanical properties required for compaction

A

Plasticity - Particles deform when compressed, increasing contact surface area between particles, therefore greater cohesion. This deformation must be plastic(i.e. irreversible) or cohesion will be lost with elastic recovery.
Brittleness - Particles fragment when compressed, increasing specific surface area and surface energy, therefore greater cohesion.

21
Q

solid properties that influence compaction

A

Crystallinity - Amorphous form usually more compactible than crystalline as less dense and molecules more mobile. Polymorphism - Thermodynamically stable polymorph usually less compactible. Morphology - Needle-like crystals less compactible than equidimensional.
Hydrates - Hydrates often more compactible than anhydrous form as water can act as plasticiser.

22
Q

Hausner ratio

A

based on bulk density and tapped density

23
Q

types of mixtures

A

Tendency to spontaneously mix - Positive mixture (mix spontaneously), negative mixture (segregate) and neutral mixture (neither)
Spatial particle arrangement - perfect mixture, random mixture and ordered mixture

24
Q

factors affecting adsorption

A

Temperature (inc = dec in ad), conc (greater solute when unionised), nature of solvent, solute (greater affinity = lower tendency to adsorb), 2nd solid present

25
Q

Advantages and disadvantages of the inhalation route

A

Smaller does can be used to produce pharmacological effect
Rapid absorption = fast onset of action
Avoids harsh GI environment thus minimises drug degradation
Avoids first pass metabolism

Requires complex delivery device = high cost
Aerosol devices hard to use
Drug absorption may be limited by the mucus layer

26
Q

gravitational sedimentation

A

sedimentation is dependant on particle size and density and residence time in the airway

27
Q

Brownian diffusion

A

small particles are bombarded by random gas molecules and produce Brownian motion which results in particle collision with the airway walls

28
Q

inertial impaction

A

particles within the air stream will impact on the airways walls rather than following the changing air flow

29
Q

Rectal excipients

A

Surface-active agents
Hygroscopicity reducing agents
Melting point controlling agents
Lubricant, preservative, colouring, diluents, adsorbents

30
Q

Vaginal route advantages and disadvantages

A

Can be used for local effects
Systematic absorption
Suitable for patients where oral is restricted
Avoids GIT environment and first pass metabolism
Self administration
Overcomes pain and inconvenience of parenteral route

Gender specific
Not popular for systemic administration
Vaginal fluid volume variation
Acidic pH may enhance degradation
Often requires use of specialist applicators
31
Q

Dissolution vs solubility

A

Transfer of molecules or ions from a solid state into a solution
Its a thermodynamically favourable process therefore gibbs must be negative

capacity of a solute to dissolve in a solvent

32
Q

Noyes-Whitney equation (predicts dissolution rate)

A

dm = DAConc diff
dt h

Mass/Time = Diffusion coefficient x SA x Conc diff / Thickness

33
Q

Hard vs Soft capsules

A

2-piece (cap and body) vs 1-piece (liquid matrix)
Filling free from large amounts of moisture, not react with shell, not leak out, good powder flow, not adhesive, filled uniformly. Dry solids and semisolids vs Lipophilic liquids, hydrophilic liquids, self emulsifying systems
8 sizes vs several

34
Q

what is a surfactant

A

surface active agent

35
Q

wilhelmy plate vs Du nouy ring

A

measures surface tension

Measures surface tension and interfacial tension - force to detach platinum ring from surface

36
Q

Suspension

A

Liquid system where the solid does not full dissolve but is suspended in the liquid medium - appears cloudy

37
Q

DVLO theory

A

Predicts the behaviour of suspension

particle movement cause by Brownian motion (diffusion), gravity (sedimentation) or external agitation

Stage 1 Pharmacy (6 decks)

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